A braking system of a vehicle can include a control unit for exercising control over the braking system of the vehicle under certain conditions. For example, during movement of the vehicle the control unit can receive signals from various sensors and, based on a control program stored in memory, control the operation of various parts of the braking system including pumps and valves. Specifically, the controller can receive signals from sensors, wherein the signals correspond to existing driving conditions. The controller can receive the signals and quantify the existing driving conditions. These quantified conditions are compared to predetermined values by a processor of the control unit and command signals are emitted in response to these comparisons. Reasons for taking control of the braking system generally relate to enhancing or optimizing vehicle dynamics.
The braking system can include a modulator or modulating pump to apply fluid pressure to a controlled wheel. When the modulator is used to apply pressure to the controlled wheel, prime and isolation valves are energized and the pump motor is turned on. Excess fluid that is pulled from the master cylinder must be relieved in some manner. This normally occurs through the isolation valve when pumping forces overcome the force of the isolation valve and fluid returns to the master cylinder. The forced opening of the isolation valve may cause noise, especially when the master cylinder is generating pressure on the opposite side of the isolation valve, as during driver braking.